Control device for the fuel feed of internal combustion engines



CONTROL DEVICE FOR THE FUEL FEED OF INTERNAL COMBUSTION ENGINES BECKERJune 10, 1941.

Filed July 30, 1937 [01/90 for,

of the air in the induction pipe 2.

Patented June 10, 1941 CONTROL DEVICI FOR THE FUEL FEED OF INTERNALCOMBUSTION ENGINES Ewald Becker, Berlin-Steglitz, Germanmassignor toAskania-Werke A. G. vormals Centralwerkstatt-Dessau and CarlBamberg-Friedenau, a

corporation of Germany Application July 30, 1937. Serial No. 156,572 InGermany August 1, 1936 4 Claims.

This invention relates to improvements in or relating to apparatus forcontrolling the fuel supply to internal combustion engines, especiallyfor aircraft engines.

As is well known, the fuel supply may be controlled in response toseveral variables, as for instance the density or pressure of the air inthe induction pipe of the engine, or the pressure of the atmosphere, i.e. in the event of aircraft the altitude. Ignoring barometric changes,the atmospheric pressure is always a function of the altitude.

The primary object of the invention is to provide controllingmeansoperating in response to the composition of the exhaust gases insuch a manner that in the gas mixture the proportion of fuel to aircannot be weakened below a predetermined limit at which the enginestarts to knock. By means of such an automatically controlling apparatusthe engine is protected in this way against damages caused byoverheating and knocking.

Other aims, objects and advantages of the present invention will bereadily understood from the following description with reference to thedrawing schematically illustrating one embodiment of the invention.

Referring now to the drawing, I is an internal combustion enginecomprising a cylinder 3 and a piston reciprocating therein, so as torotate in a well known manner the crank-shaft of the engine. Two valvesare provided for controlling the inlet and the exhaust respectively.In'the induction pipe 2 a throttle valve 3 is arranged for controllingthe air sucked in by the motor.'

I is an injection nozzle adapted to inject the fuel into the air flow,said nozzle communicating by means of a pipe 6 with a fuel pump 3 of anyconvenient type driven from the crank shaft of the engine as shownin thedrawing. The effective stroke of the pump 3 may be varied in a wellknown manner by "means of an adjusting member so as to vary the amountof fuel in- .iected into the air flow. According to the presentinvention, said adjustingmember 3' will be automatically controlled inaccordance with any variable, as for instance the density or pressureFurthermore, a controlling device responsive to the composition ofthe'exhaust gases will be superposed on said primary controlling deviceas will now be more fully explained.

In a casing III a capsule system is mounted comprising a plurality ofindividual capsules 3, 9. The casing ll communicates by means of aconduit H with the induction pipe 2 so that any change in the airdensity or pressure in the pipe 2 results in an extension or contractionof the capsule system, thereby displacing a pin i2 and theabove-mentioned adjusting member 5' of the fuel pump 3 as shown and morefully explained in detail in my copending patent application Ser. No.156,571 of July 30, 1937.

The capsule system is mounted in such a manner that it may be displacedin axial direction so as to act only as a transmitting 'member totransmit any additional controlling movement to the pin l2 and theadjusting member 3', as is likewise more fully explained in saidabovementioned patent application. In the embodiment shown ascrew-threaded ring H is threaded in the casing ill; to said ring a pin31 is fastened which is linked to a link 33 which is connected to apiston rod 34 of a servo-motor piston 35 driven by a pressure fluid, e.g. 011. The flow of the pressure fluid to the servo-motor will becontrolled by means of the well known "Askani a jet pipe relay 28, thejet pipe of which is supplied with the pressure fluid through a pipe 3|connected to any convenient pressure source. The pressure fluid jetflowing-out of the Jet pipe 28 is variably admitted in accordance withthe controlling device acting upon the let pipe to two channels 32, 33leading to both sides of the servo-motor 36 respectively. In the neutralor middle position of the jet pipe, as shown in the drawing, thepressure in the channel 32 is equal to that in the channel 33., As soonas the jet pipe is deflected in the manner to be described later' onfrom said neutral position in the one or the other direction, theservo-motor piston 35 will be correspondingly displaced, therebyrotating by means of the pin 31 the screw-threaded ring ll, thusdisplacing the adthe transmitting capsule member and pin l2.

The controlling means acting upon the jet pipe 29 is responsive to thevariation in the composition of the exhaust gases in the followingmanner.

The means responsive to the variation in composition of the exhaustgases comprise a casing 16 divided by a wall It into two chambers I7. I3, each chamber being provided with a resistance wire I9, 20,respectively. The chamber l'l communicates with the exhaust pipe 4 ofthe engine by means of a pipe IS, a filter I! of any convenient'typebeing inserted in said pipe. In this way a part of the exhaust gasesflows through the pipe I5 into the chamber I1 and out of this chamberback to the exhaust pipe 4 by means of a pipe 24. The second chamber itcontains a suitable comparison gas, e. g. air. The resistance wires I9,20, as mentioned above are each arranged as a branch of a Wheatstonebridge. The two other branches thereof are shown as at 2|, 22. Thebranches of this Wheatstone bridge will be heated to a predetermineddegree by means of any source of current as at 25. As shown in thedrawing, two lines 26, 21, respectively, lead from the Wheatstone bridgeto a solenoid 28, the armature of which is operatively connected to thejet pipe 29.

The device described operates as follows:

The current source 25 heats the resistance wires i9, 20 to apredetermined degree. The tempera ture of the wires I9, 20 remainsconstant, unless the composition of the exhaust gases changes. Anychange in the composition results in a change of temperature of theresistance wire l9 due to the fact that any change in composition causesa change in thermal conductivity of the exhaust gases. A deviceresponsive to the composition of the exhaust gases is well known per seas for instance shown and described in U. S.

Patent No. 2,040,778, issued May 12, 1936. If

for instance the proportion of hydrogen in the exhaust gases increases,then the thermal con-.

ductivity of the exhaust gases likewise increases so that thetemperature of the resistance wire l9 decreases, in consequence thereofthe equilibrium of the Wheatstone bridge will be disturbed so that acurrent will flow through the lines 29, 21, thereby exciting thesolenoid 28 and changing. the position of the Jet pipe 29 with referenceto the entrance openings of the channels 32, 33. Accordingly in this waythe let pipe 29 follows the changes in the composition of the exhaustgases.

In order to have a predetermined position of the jet pipe 29 at apredetermined composition oi the exhaust gases a well known restoringsystem is provided including an arm 34' fastened to the rod 34 of theservo-motor piston 35 and a spring 39 arranged between said arm 34' andthe jet pipe 29 so as to exert on the jet pipe a restor-' ing force inopposition to the controlling force of the solenoid. 7

As shown in the drawing, the servo-motor piston 36 does not only controlthe effective stroke of the fuel pump 6. but also the timing ofignition. For this purpose the rod 49 of the piston 35 is operativelyconnected to a distributor II by means of a link 49, said rod 9 beingprovided for adiusting the setting of the distributor 48 of the ignitionapparatus in the well known manner.

The capsule system 9 mentioned above controls the fuel supply to themotor in accordance with the density or pressure of the air in theinduction pipe 2. This primary controlling system will be so adjustedthat the proportion between fuel and air remains at its optimum or atany desired point for achieving-as far as possible-an economicalworking. Should this primary controlling system for any reason tend todecrease the amount of fuel below said proportion in accordance with thedensity or pressure of the air in the induction pipe 2, the secondarycontrolling means operating in response to the composition of theexhaust gases becomes effective in such manner that the proportionremains above said proportion.

In the event it is desirable, for instance in emergency cases when theplane is falling or to keep the motor going without fuel economy or toobtain a richer mixture, to pass said proportion the pilot may interruptthe flow of pressure fluid through the conduit 3| to the jet pipe 29 soas to render ineffective the secondary controlling means. In the conduit3| a valve is provided as diagrammatically shown at H. The flow of fluidthrough conduit 3| is out of! by operating valve ill whereby the relaybecomes inoperative but the piston 35 may then be moved manually by thearm 34' for instance and it will remain in such position by friction orit may be suitably locked in any set position. This will eliminate theeffect of the exhaust gas analyzer.

Besides the capsule system 9 any other primary control device may beused for controlling the fuel supply. In the embodiment shown in thedrawing-the adjusting member 5' of the fuel pump I will be alsocontrolled in dependence on the temperature of the exhaust gases. Thistemperature responsive means comprises a casing 49 arranged in theexhaust pipe 4, said casing contains any suitable liquid, the vaporpressure of which is responsive to the temperature. Accordingly abellowsl2 communicates with the casing 40 by means of a conduit 4| so that thebellows will be extended or compressed in response to the temperaturesof the exhaust gases, thereby actuating the rod 43, a link 44 and an armI! attached to the screw-threaded capsule supporting member l3. Anyrotation of the member l3 results in an axial displacement of thecapsule system 9 and an adjustment of the fuel pump controlling member5.

It is to be noted that the embodiment shown may be modified withoutdeparting from the spirit of my invention as defined in the appendedclaims.

What is claimed is:

i. The combination in an internal combustion engine having an airthrottle valve in the air intake manifold, of fuel quantity controlmeans regulated by a device responsive to the pressure in the intakemanifold on the engine side of the air throttle valve, and means foradjusting the pressure responsive device so as to modify its effect onthe fuel control means, said acflusting means being responsive tovariations in the composition of the exhaust gases.

2. The combination in an internal combustion engine having an airthrottle valve in the air intake manifold, of fuel quantity controlmeans regulated by a device responsive to the pressure in the intakemanifold on the engine side of the air throttle valve, and a jet piperelay and servomotor of which the latter is connected to thepressure-responsive device for adjusting the latter so as to modify itseffect on the fuel control means, said jet pipe relay being responsiveto variations in the composition of the exhaust gases.

3. The combination in an internal combustion engine having an airthrottle valve in the air intake manifold, of fuel quantity controlmeans regulated by a device responsive to the pressure in the intakemanifold on the engine side of the air throttle valve, a jet pipe relayand servomotor of which the latter is connected to the pressureresponsive device for adjusting the latter so as to modify its effect onthe fuel control means, said jet pipe relay being responsive tovariations in the composition of the exhaust gases, and emergencycontrol means for rendering said jet pipe relay and servo-motorineil'ective on said pressure responsive device.

. side of the air, throttle valve, a jet pipe relay and servo-motor ofwhich the latter is connected to the pressure responsive device foradjusting the latter so as to modify its effect on the fuel controlmeans, said jet pipe relay being responsive to variations in thecomposition 0! the exhaust gases, and ignition adjusting meansoperatively connected to the servo-motor to adjust the ignition timingin dependence on the composition of the exhaust gases.

EWALD BECKER.

